The present invention relates to an image forming apparatus provided with an automatic document feeder, and in particular, to an image forming apparatus capable of obtaining a print (copy) sheet group corresponding to a state in which a certain original sheet group receives another original sheet to be inserted between arbitrary pages of the original sheet group.
In order to obtain a print sheet group corresponding to a state in which a certain original sheet group receives another original sheet to be inserted between arbitrary pages of the original sheet group by means of an image forming apparatus provided with an automatic document feeder, there is often adopted the method of preparatorily inserting another original sheet into the original sheet group, setting the resulting sheet group on the automatic document feeder and executing copying. This method has no problem when the original sheet group and the inserted original sheet have the same size. However, when they have different sizes, the original sheets cannot be conveyed depending on the type of the automatic document feeder, or productivity in print formation might sometimes be extremely reduced. For example, if it is tried to successively feed original sheets of different widths by means of an automatic document feeder based on the center-sheet-feed standard, then the original sheet having the narrower width cannot be regulated in the widthwise direction, and this causes original sheet jam (paper jam). If original sheets of different sizes are concurrently stacked on a sheet feed tray, then the original sizes cannot be discriminated by a sensor on the sheet feed tray. Therefore, the image forming apparatus of the type which takes the original image while moving the original has the practice of once feeding (merely conveying) the original sheet so as to detect the original size by means of a sensor on the conveyance path and thereafter feeding the sheet again for the reading of the original image. For the above reasons, a processing time for reading the original is prolonged, causing a reduction in productivity.
In order to provide a method for resolving these problems, there has been a proposed digital copying machine that once stores image information of original sheets into a memory in units of pages and designates an arbitrary position of the stored image information by an insertion position designating button on an operation panel, thereby allowing other image information to be inserted in the position (the prior art reference of Japanese Patent Laid-Open Publication No. HEI 5-292268).
However, according to the above-mentioned digital copying machine, an operator is required to input the original insertion positions one by one via the operation panel or the like, and this has the problem that a long time is required for the input work. Furthermore, the problem that the original sheet has not been inserted in the desired position or a similar problem tends to occur due to an erroneous input.